The invention relates to a method for the hot repair of the protective layer provided on the permanent lining of a tundish of a continuous casting plant.
It has proved advantageous for tundishes to provide the permanent lining with a wear resisting layer, a so-called working lining, which acts as a protective layer for the permanent lining. This working lining is renewed from time to time in order that the permanent lining below it will not be affected. So far, the renewal of the working lining has been carried out in the cold state of the tundish, i.e. by manually scooping out the tundish after having tilted out the molten metal and slag residues still present in the tundish immediately after the termination of casting, and subsequently applying the working lining. To this end it is necessary to cool the tundish over a longer period of time, by taking care that the temperature of the tundish does not sink to below a certain height in order to keep thermal losses low. Scooping out, therefore, due to the residual heat of the tundish, is an extremely exhausting and also long operation.
A further disadvantage of the known method of repair is the necessary long heating of the relatively cold tundish (in order to prevent an immediate solidification of the metal poured into the repaired tundish), with a certain temperature curve having to be observed. A rapid heating of the tundish is not possible, since the tundish would be damaged by the thermal stresses occurring.
It is known with tundishes (Austrian Pat. No. 335,647) to form the working lining by plates with a low thermal conductivity and a low thermal capacity. A granular material, e.g. quartz sand, is provided between the permanent lining and the working lining. Such plates have to be joined by refractory mortar, which requires much work.
It is furthermore known to provide the plates of the working lining with tongue-and-groove connections, thus rendering the placing simpler; yet, such plates are complex in their production.